The invention is designed for use in high performance, rigorous environments, such as automobile racing and certain industrial applications. The environment wherein the invention is particularly adapted for use is characterized by relatively large engines of high power having one or more carburetors and which have a correspondingly high fuel demand, and wherein the fuel demand changes rapidly. However, where carburetors are used, which is the environment of the invention, the fuel needs to be supplied at a relatively low pressure while at the same time being supplied in high volume. Further, this high volume of fuel must be supplied in a manner which is highly responsive to the engine's rapidly changing demand for fuel and, all of this needs to be done at a relatively low pressure. In carburetted engines, excess pressure at the carburetor can cause flooding of the carburetor. Such flooding, especially in high power large fuel consumption engines, can cause a fire, at the worse, and will cause disruption of engine operation, at the minimum.
It has been heretofore unknown to use a return type pressure regulator in regard to such carburetted systems, although return type pressure regulators have been used with engines having fuel injection systems.